Pulp-strainer.



No. 784,743. PATENTBD MAR. 14, 1905. F. E. HEMINGS.

PULP STRAINER.

APPLICATION IILBI) MAY 21, 1903.

3 SHEETS-SHEET 1.

No. 784,743. PATENTED MAR. 14, 1905.

F. B. HEMINGS.

PULP STRAINER.

APPLICATION FILED MAY 21, 1903.

'4 flFETTS-SHEET 2.

UNIT D STATES Patented March 14, 1905.

PATENT OFFICE.

FREDERIOK'ELMER HEMlNGS, OF BROWVNVILLE, NEW YORK, ASSIGNOR OF ON E-HALF TO CHARLES N. SHERMAN, OF XVATERTOWN, UElV YORK.

PULP-STRAINER.

SPECIFICATION forming part of Letters Patent No. 784,743, dated March 14, 1905.

Application filed May 21, 1903. Serial No. 158,106.

Vl'o all whom, it may concern:

Be it known that I, FREDERICK ELMER HEM- INGS, a citizen of the United States, and a resident of Brownville, in the county of Jefferson and State of New York, have invented new and useful Improvements in Pulp-Strainers, of which the following is a specification.

This invention relates to that class of pulp strainers or screens which contain a station- IO ary screen and below the same a pneumatic pulsating or pumping mechanism by which the downward passage of the pulp through the slits or apertures of the screen-plates is expedited and the slits of the screen-plates are 5 kept open.

One object of this invention is to improve the character or quality of the separation in such manner that slivers, knots, dirt, and other refuse and impurities are more certainly 2O prevented from passing'through the slits of the plates with the fine pulp, whereby a cleaner and more uniform pulp is produced. This object is attained by providing the machine with an auxiliary or secondary screen 5 which is arranged at a lower level than the main or primary screen, so that the stock or pulp is first strained on the main or primary screen, and the residue, which does not pass through the main screen, is further strained 3 on the lower auxiliary or secondary screen.

Another object of this invention is to provide means for regulating or controlling the action of the pneumatic pumping or pulsating mechanism on the slits of the screen-plates.

It has been found that the compression of the air which takes place in the space or compartment underneath the screen-plates during the upward stroke of the diaphragm or bellowsplate often vents itself to a large extent in a 4 downward direction upon the surface of the screened pulp or stock in such space or compartment, whereby the blast action in an upward direction through the slits of the screenplates is correspondingly impaired. This object is attained by regulating the area or opening of the passage or spout through which the screened pulp is discharged.

In the accompanying drawings, consisting of three sheets, Figure 1 is a longitudinal see- I tional elevation in line 1 1, Fig. 3, of a pulp- 5 strainer provided with my improvements. Fig. 2 is a vertical transverse section in line 2 2, Fig. 3. Fig. 3 is a top plan view of the machine. Fig. 4: is a vertical longitudinal section in line a i, Fig. 3. Fig. is a fragmentary sectional elevation of one end of the gate, on an enlarged scale. Fig. 6 is a vertical cross-section of the same in line 6 6, Fig.

5. Fig. 7 is a fragmentary top plan view of one end of the gate. Fig. 8 is a fragmentary 00 side elevation of the screen-frame, showing the upright slot in which the arm of the gate is arranged. Fig. 9 is. a fragmentary longitudinal vertical section through the How-box and connecting parts in line 9 9, Fig. 3, on a 5 reduced scale. Fig. 10 is a vertical transverse section through the flow-box and connecting parts in line 10 10, Fig. 9. Fig. 11 isa top plan view of a modified construction of the machine. Fig. 12 is a longitudinal vertical 7 section in line 12 12, Fig. 11.

Like letters of reference refer to like parts in the several figures.

A represents the main or primary screen provided with a number of slitted or perforated screen-plates a, supported in any suitable manner in. a screen'supporting frame B, having cross-pieces 7) b. For the purpose of simplifying the representation the main screen is shown as provided with four screen-plates, but in practice a greater number is usually employed. V

The space below the screen-plates is preferably divided, as usual, into several independent compartments orsuction-chambers O, 3 5 into which the strained pulp passes, although asingle space or compartment may be used.

D represents the flexible diaphragms which form the bottoms of these compartments, and D represents the bellows-plates, to whichthe 9 diaphragms are secured. The up-and-down movement is produced in these diaphragms and bellows-plates by any suitable mechanismfor instance, as shown, by connectingrods d, extending downwardlyfrom theplates to cams cl on a horizontal actuating-shaft (Z and the springs 0, arranged between bridgetrees a, secured to the body-frame E, and nuts c on the connecting-rods. This well-known i this bellows-plate. h the cam on the shaft d construction of the pneumatic pulsating or pumping mechanism is preferred; but any other mechanism suitable for the purpose may be employed.

The outlet passages through which the strained pulp escapes from the compartments C are constructed in any well-known or suitable manner. Those shown in the drawings are constructed as described and shown in Letters Patent No. 530,886, dated December l1. 1894:, to D, B. Gotham, and consist of downwardly-extending outlet-passages f, opening along the contiguous edges of two adjacent compartments or suction chambers into the top of a transverse spout F, which turns upwardl y at the front of the machine and connccts with an elevated flow or discharge box F. The latter is provided with the usual outlet f for the screened pulp .and the usual overflow partition by which the level of the screened pulp in the compartment is maintained at the proper distance below the screen-plates for forming the desired air-space and sealing the same.

The flow-spout F is provided near the flowbox with an adjustable valve or regulating device of any suitable construction, whereby the How area or opening of the submerged spout can be increased or reduced. If it should be found that the upward blast through the slits of the screen-plates isnot sufficiently strong to keep the slits clear, the flow area of the flow-spout is reduced by partially closing the valve f. By thus throttlingthe submerged discharge-passage for the screened pulp the resistance to the movement of the screened pulp in a downward direction isincreascd, and this causes the air-pressure underneath the screen-plate to act more strongly in an upward direction, thereby increasing the intensity of the blast. ()n the other hand, if the upward blast is too strong it can be reduced by opening the valve, because this lessens the resistance to the downward movementof the liquid. As shown in the drawings, thevalve f is arranged between vertical guidesf" on the inner wall of the (low-box and held adjustably. in position by a screw-bolt f, which passes through an upright slot f in the valve.

(1i represents the auxiliary screen, which is arranged in the screen-frame B at one side of the main screen and at a lower level, the two screens being separated by a partition 6 This auxiliary screen is constructed in substantially the same way as the main screen, but can be smaller in area, and its screen-plates r are preferably provided withcoarser slits or apertures. As shown in the drawings, this auxiliary screen has two screen-plates and below the same a single suction chamber or compartment GI, the bottom of which is formed by the flexible diaphragm H, secured to the bellows-plate H.

l1. represents the connecting-rod secured to and 2: the spring between the bridge-tree i and nut xi.

1 represents the outletpassage for the strained pulp leading from the compartment G to the flow-spout K, which is connected at the front with the flow-boX K, having the usual outlet li and overflow-partition L The flow-spout of this compartment is provided with a regulating-valvef, as above described.

The liquid pulp or stock to be strained is fed upon the main screen, along one of the longitudinal sides thereof, so that the material flows over the individual screen-plates from one end of each plate to the other. At the opposite longitudinal side the main screen is provided with a gate L, which stands With its lower edge above the screen-surface and allows a layer of liquid of the desired depth to escape from the primary screen and maintains a certain depth of liquid on the primary screen. This gate is made vertically adjustable by any suitable meansfor instance, as shown, by laterally projecting arms Z, which extend through vertical slots Z in the screen-frame B and are provided with clamping-nuts Z Figs. 5, 7, and 8. The gate is preferably composed of a wooden head Z and a metallic plate Z, projecting from the lower side of the head, Fig. 6.

M represents a trough, gutter, or conduit which is arranged along the rear of the screenframe in rear of the gate L and which conducts the material which escapes over the tail or discharge end of the main screen to the aux iliary screen G.

A sufficient layer of liquid material is maintained on the main screen to keep the screenplates of the same well covered. The fine pulp is drawnthrough the slits or apertures of the main screen in a well-known manner, while the slivers, knots, and other coarse refuse and impurities are floated and pass off with the surplus liquid into the trough M, by which this material is delivered upon the auxiliary screen. This trough is arranged slightly below the level of the primary or main screen and descends toward the secondary screen, as shown in Figs. 2 and 4, so that the surplus liquid drains freely or in a current from the main screen and carries with it the floating coarse particles, which are delivered by this liquid to the secondary screen. The latter separates the remaining line pulp from the slivers and other coarse refuse and impurities contained in this materlal. The strained pulp coming from the auxiliary screen is preferably returned to the chest or receiver from which the main screen is supplied, and the coarse refuse is raked off from time to time.

The arrangement of the auxiliary or secondary screen below the level of the main or primary screen enables the material on the main screen to be treated irrespective of that on the auxiliary screen. The thickness of the layer on the main screen is readily maintained at such'a height that the coarse particles and other refuse are floated and do not descend to the screen-surface, in which case there would be danger of objectionable particles passing with the fine pulp through the slits ofthe screen-plates and impairing thequality and color of the strained pulp. The strained pulp or stock coming from the main screen is therefore practically free from coarse and discolor ing particles and impurities. Any fine pulp which escapes over the discharge end of the main screen with the refuse is recovered by the auxiliary screen and returned for further treatment to the main screen or is otherwise utilized.

When a longer travel of the material over the main screen is desired than can be obtained by passing the material over the screen from one of its longitudinal sides to the other, as is done in the machine represented in Figs. 1 to 4, the machine represented in .Figs. 11 and 12 can be employed. In this machine the material is fed upon the main screen at one of the ends or short sides thereof, and the gate is arranged at the opposite end of the main screen between the latter and the auxiliary screen. The material which tails off from the main screen passes from the latter directly upon the auxiliary screen, and the intermediate trough or conduit is dispensed with.

In Figs. .11 and 12, N represents the main screen, 0 the auxiliary screen, and P the gate arranged between these screens. This gate is arranged transversely in the screen-frame above the tail end of the main screen. The construction of the compartments underneath the screen-plates, the pumping mechanism, and the outlet-passages is the same as that in the machine represented in Figs. 1 to 4:.

My improved machine contains a main and an auxiliary screen in the same supportingframe and is a compact and convenient machine which is especially desirable in connection with a paper-machine, although it is also applicable to other usesfor instance, for strainingwood-pulp and similar material.

I claim as my invention- 1. The combination of a primary screen, a secondary screen arranged at a lower level than the primary screen, pulsating means for each screen, a gate which is arranged above the discharge end of the primary screen and allows the surplus liquid and unscreened material to escape underneath its lower edge, and means for conducting such surplus liquid and unscreened material to the secondary screen, substantially as set forth.

2. In a pneumatic pulsating pulp-strainer, the combination of a supporting-frame, a primary screen and a secondary screen arranged therein side by side, the secondary screen at a lower level than the primary screen, separate pneumatic pulsating devices arranged .screen, and an adjustable gate which is arranged over the discharge end of the primary screen with its lower edge above the same and allows the unscreened material to escape underneath its lower edge, substantially as set forth.

3. The combination of a primary screen, a secondary screen arranged at one side of the primary screen and at a lower level, pulsating means for each screen, and a connectingtrough which is arranged below the level of the discharge end of the primary screen, to cause the surplus liquid and unscreened material to drain from said primary screen into said trough, and which conducts such surplus liquid and unscreened material to the secondary screen, substantially as set forth.

4. The combination of a primary screen, a secondary screen arranged at one side of the primary screen and at a lower level, the receiving end of the secondary screen being arranged in line with the discharge end of the primary screen, pulsating means for each screen, and a connecting-trough which is arranged below the level of the discharge end of the primary screen to cause the surplus liquid and unscreened material to drain from said primary screen into said trough, said trough extending along the discharge end of the primary screen and the receiving end of the secondary screen, substantially as set forth.

5. In a pulp-strainer, the combination of a primaryscreen and a secondary screen arranged side by side, the discharge end of the primary screen being in line with and higher than the head end of the secondary screen, a connecting-trough extending along the discharge end of the primary screen and the head end of the secondary screen, and an adjustable gate which is arranged over the discharge end of the primary screen with its lower edge above the same and allows the unscreened material to escape underneath its lower edge, substantially as set forth.

6. In a pulp-strainer, the combination of a screen, a pneumatic pulsating mechanism arranged beneath the same, a discharge-passage for the screened pulp which terminates in an elevated discharge below the screen-level and by which said discharge-passage is kept submerged and an air-space is maintained below the screen, and means for increasing or reducing the flow area of said submerged passage, thereby regulating the pneumatic action on the screen, substantially as set forth.

7. In a pulp-strainer, the combination of a screen, a pneumatic pulsating mechanism arranged beneath the same, a flow-passage for controlling the flow area thereof, substantially the screened pulp, a flow-box connected with as set forth. said spout and having an elevated discharge \Vitness my hand this 18th day of May,l903.

below the screen-level by which said passage FREDERICK ELMER HEMINGS. is kept submerged and an air-space is mainitness esz tained below the screen, and a regulating- G. D. \V RIGHT,

valve arranged in said submerged passage and A. M. POWELL. 

